C3 - quantitative chemistry

• How do you calculate percentage mass

  ((Mass of element X number of atoms) ÷ Mr ) x 100
• How do you calculate concentration with mass

  Concentration= mass/volume
• How do you calculate concentration using moles

  Concentration= mole/volume
• How do you calculate gas volume

  Volume = mole x 24
• Why will the percentage yield always be less than 100

  • Some products may be left behind on apparatus
  • The reaction may not be fully complete
• How do you calculate percentage yield

  (Actual/theoretical) X 100
• How do you calculate atom economy

  (Mr of useful product ÷ Mr of all reactants) X 100
• How do you calculate maximum mass step by step

  1. Moles = mass/Mr
  2. Mole ratio
  3. Mass = Mr x mol
• What is the law of conservation of mass

  No atoms are made or lost during a chemical reaction

  So mass of the products is equal to the mass of the reactants
• Why don't gases follow the law of conservation of mass

  It can escape changing the mass

  A gas on the right of the equation decreases the mass
• How do you convert cm³ into dm³

  ÷ by 1000